In an exposure apparatus used for manufacturing a semiconductor device (semiconductor integrated circuit), due to the miniaturization of patterns, Extreme Ultra Violet (EUV) having a shorter wavelength than ArF has been used. Due to the shortened wavelength of exposure light, the resolution of exposure transcription pattern is increased, and fine pattern formation is enabled. Meanwhile, due to the shortened wavelength, an apparatus configuration or an exposure method is changing from a conventional exposure method. As a greatly changing point, there may be a projection optical system. In a conventional projection optical system, a refractive lens is used. However, in EUV exposure, EUV light does not pass through the refractive lens due to a relation between a light absorption and a refractive index. For this reason, in an EUV exposure apparatus, a conventional refractive lens cannot be used, and a catoptric system such as a mirror is used.
In manufacturing a mirror, a mirror surface cannot be finished to be completely flat. Thus, roughness is formed on the mirror surface. When the roughness is formed, exposure light irradiated on the mirror surface is diffusely reflected during pattern exposure, and an unintended region on a resist surface of a wafer is exposed to scattered light. Therefore, a contrast on a wafer is lowered, a pattern image is blurred. As a result, there occurs a problem that a finished dimension (finished pattern shape) is not formed as desired.
The exposure light diffusely reflected on the mirror surface is referred to as flare, which is considered as one of main factors that degrade the pattern formation accuracy in the EUV exposure. Also, since an amount of flare is the cause of exposure of scattered light from surroundings, an amount of flare is varied by a surrounding pattern density. Therefore, even in the same mask pattern, there occurs a problem that a finished dimension is different by a place (pattern arrangement position). For this reason, there is a need for technology that calculates a flare map at high speed and with high accuracy.